Multi-lumen heat transfer catheter systems

ABSTRACT

Heat transfer catheter apparatus and methods of making and using same are disclosed wherein fluid connection means is provided between the distal portions of two adjacent, thin-walled, high strength fluid lumens to define a closed loop fluid circulation system capable of controlled delivery of thermal energy to or withdrawal of thermal energy from remote internal body locations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.11/167,036 filed Jun. 24, 2005, now pending, which is a continuation ofU.S. patent application Ser. No. 10/229,243, filed Aug. 26, 2002, nowabandoned, which was a division of U.S. patent application Ser. No.09/309,052, filed May 10, 1999, now U.S. Pat. No. 6,440,158, issued Aug.27, 2002; which is a division of U.S. patent application Ser. No.08/453,066, filed May 26, 1995, now U.S. Pat. No. 5,902,268, issued May11, 1999; which in turn was a division of U.S. patent application Ser.No. 08/287,114, filed Aug. 8, 1994, now U.S. Pat. No. 5,624,392, issuedApr. 29, 1997. The complete contents of these earlier patents and patentapplications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to heat transfer catheterapparatus for internal body applications, and more particularly, tocatheters adapted for delivering heat transfer fluids at temperaturesabove or below normal body temperatures to selected internal body sitesthat are relatively remote from the point of entry into the body forspecialized medical applications. The heat transfer catheters of thisinvention may, in one embodiment, comprise fluid lumens that have verythin-walled, high strength sidewalls that are substantially inelastic.In an alternative embodiment, the fluid lumen sidewalls may beelastomeric. In either case, the fluid lumens are readily inflatableunder fluid pressure and readily collapsible under vacuum. The heattransfer catheter apparatus of this invention may comprise multi-lumenunits having two or more lumens.

The heat transfer catheter apparatus of this invention may also, indifferent embodiments, be used alone or in conjunction with othermedical apparatus. The heat transfer catheter apparatus of thisinvention may also, in different embodiments, comprise single ormulti-lumen dilatation balloons.

It is well known in the art to prepare and use catheters for a varietyof medical applications. In one familiar application, inexpensive,disposable catheters having one open end and one closed end are utilizedas protective sheaths for various medical instruments. The use of suchelongated, tubular sleeves as protective sheaths can minimize the costsand problems associated with cleaning and sterilizing medicalinstruments, such as endoscopes, between uses. In the case of medicaloptical instruments, such as endoscopes, the protective sleeves mayinclude a “window” portion designed to align during use with the opticalportion of the medical instrument.

Typical of the prior art in this field are U.S. Pat. Nos. 4,646,722(Silverstein et al.) and 4,907,395 (Opie et al.). The Silverstein et al.patent teaches the use of an endoscope sheath comprising a flexible tubesurrounding the elongated core of an endoscope. The flexible tube has atransparent window near its distal end positioned in front of theviewing window of the endoscope. An alternative embodiment of theSilverstein et al. sheath for use with side-viewing endoscopes is shownin FIG. 10 of that patent. In this embodiment, the sheath 110 comprisesan end cap 112 of relatively rigid material mounted at the end of aflexible cylindrical tube of elastomeric material 114 formed into a roll116. The end cap 112 includes a pair of transparent windows 118, 120.The later Opie et al. patent is essentially an improvement inventiondirected to a method of packaging and installing the endoscope sheathsof the Silverstein et al. patent.

U.S. Pat. Nos. 3,794,091 (Ersek et al.) and 3,809,072 (Ersek et al.) aredirected to sterile sheaths for enclosing surgical illuminating lampstructures that have elongated light transmitting shafts. The sheaths inErsek et al. are fabricated from films of flexible plastic material,such as vinyl tubing, polyethylene or polypropylene. Ersek et al. prefera wall thickness of between three and six mils for the requireddurability, rigidity and transparency. The tip end portion 20 of thesheath is described as a “generally rigid lens element” sealed to thesheath in a continuous sealing line 21 by thermal welding or adhesivebonding. U.S. Pat. No. 4,957,112 (Yokoi et al.) describes an ultrasonicdiagnostic apparatus, the distal end portion of which includes a cover24 made of a thin, hard, polyethylene sheet that has a window portion 34along a sidewall. U.S. Pat. No. 4,878,485 (Adair) describes a rigid,heat sterilizable sheath S that provides an outer casing for a videoendoscope. The sheath includes a viewing window 32, a flat discpositioned at the distal end in the optical path of the endoscope. U.S.Pat. No. 4,819,620 (Okutsu) describes an endoscope guide pipe which isrigid and formed from a transparent material such as glass or plastic.In one embodiment shown in FIG. 6 of that patent, a pair of slots in thesidewall of the guide pipe is filled with a transparent material, suchas glass, to define a window section 12 f. U.S. Pat. No. 4,470,407(Hussein) describes a flexible, elongated tube with an elastomericballoon sealingly mounted at the distal end of the tube for enclosing anendoscope. Inside the body, the balloon can be inflated to facilitateendoscope viewing. U.S. Pat. No. 4,201,199 (Smith) describes arelatively thick, rigid glass or plastic tube 10 which fits over anendoscope. The distal end of the tube in the Smith patent is providedwith an enlarged, sealed bulb 12 having a radius of at least 3-4 mm toreduce optical distortion caused by a too-small radius of curvature.U.S. Pat. No. 3,162,190 (Del Gizzo) describes a tube 19, made frommolded latex or similar material, through which an optical instrument isinserted. Viewing is through an inflatable balloon element 24 mounted atthe distal end of the tube. U.S. Pat. No. 3,698,791 (Walchle et al.)describes a very thin, transparent microscope drape which includes aseparately formed, optically transparent, distortion-free lens forviewing.

In another familiar application, multi-lumen balloon catheters areutilized as dilatation devices for dilating a blood vessel, e.g. acoronary artery, or other body canal. The use and construction ofballoon catheters is well known in the medical art, as described forexample in U.S. Pat. No. Re. 32,983 (Levy) and No. 4,820,349 (Saab).Other patents generally showing the application of various types ofballoon catheters include U.S. Pat. No. 4,540,404 (Wolvek), No.4,422,447 (Schiff), and No. 4,681,092 (Cho et al.).

It is also well known in the medical art to employ catheters havingshafts formed with a plurality of lumens in instances where it isnecessary or desirable to access the distal end of the catheter or aparticular internal body location simultaneously through two or morephysically separate passageways. For example, U.S. Pat. No. 4,576,772(Carpenter) is directed to increasing the flexibility orarticulatability of a catheter having a shaft formed with a plurality oflumens that provide distinct conduits for articulating wires, glassfiber bundles, irrigation, and vacuum means.

It is also known, as shown in U.S. Pat. No. 4,299,226 (Banka) and No.4,869,263 (Segal et al.), to employ multi-lumen catheters with aballoon. The Banka patent shows a double-lumen catheter shaft of coaxialconstruction wherein the outer lumen carries saline solution to inflatea balloon, and an inner lumen, located coaxially inside the outer lumen,is adapted to receive a stylet or guide wire. In the Banka patent, thedouble-lumen dilatation catheter is designed to be coaxially containedwithin the single lumen of a larger diameter guide catheter. In theBanka device, each of the three coaxial lumens is a separate, distinctpassageway without any means for fluid passage between two of thoselumens. Such fluid passage between lumens could occur only accidentallyin the event of a rupture of one of the lumens, and such results areclearly contrary to the intent of that patent.

The Segal et al. patent shows a more complex dilatation catheterapparatus having five separate, non-coaxial lumens (FIGS. 1 and 2 ofthat patent) extending through the catheter, including a ballooninflation lumen 18, a distal lumen 17, a wire lumen 22, a pulmonaryartery lumen 26, and a right ventricular lumen 28. Lumens 17 and 18extend the entire length of the catheter from the proximal extremity tothe distal extremity. Lumen 17 exists through the distal extremity 14 bof the catheter. The distal extremity of lumen 18 is in communicationwith the interior of balloon 16 to permit inflation and deflation.Lumens 22, 26 and 28, on the other hand, only pass partly or completelythrough the larger diameter, proximal portion 14 a of the catheter. TheSegal et al. catheter apparatus is prepared by extrusion (col. 2, lines53 and 54). Multi-lumen catheters in conjunction with a balloon orinflatable element have also been adapted for a variety of specialusages. U.S. Pat. Nos. 4,994,033 (Shockey et al.) and 5,049,132 (Shafferet al.) are both directed to balloon catheters adapted for intravasculardrug delivery. Both of these patents employ a similar concentric,coaxial, double balloon construction surrounding a central lumen. Thelarger, outer balloons in both cases include a set of apertures for thedelivery of medication to surrounding tissue when the catheter is inplace. No fluid connection or passageway is provided between the innerand the outer balloons or the lumens serving those balloons in thesepatents.

U.S. Pat. No. 4,681,564 (Landreneau) teaches another type of multi-lumencatheter in conjunction with a balloon element. In this patent, a firstfluid passage is in communication with the balloon element so as toselectively inflate or deflate it; a second, separate fluid passage hasoutlet openings at its distal end for purposes of delivering medicationor other treating fluid to the body space; and, a third, separatepassage has drain openings communicating with the body space so as todrain excess fluids. This patent thus describes a catheter loop wherebytreating fluid enters the body through a first lumen and some portion ofthat fluid leaves the body through a separate second lumen. But, this isclearly not a closed loop in the sense that some portion of the treatingfluid remains in the body, and all of the treating fluid must passthrough a portion of the human body on its way from the inlet lumen tothe drainage passage. Such treating fluid certainly could not containtoxic substances which would poison or harm the body.

U.S. Pat. Nos. 4,581,017 (Sahota) and 5,108,370 (Walinsky) are bothdirected to perfusion balloon catheters designed to maintain blood flowthrough a blood vessel during a dilatation procedure, for example anangioplasty. In Sahota, a hollow, central shaft passes through theinterior of the balloon element, and apertures in the side wall of thecatheter shaft upstream and downstream from the balloon permit blood toflow into the shaft, past the balloon, and back into the blood vessel. Asmall, separate tube connected to the balloon is used to inflate anddeflate the balloon. No fluid connection is provided between the balloonand the central shaft. A generally similar balloon catheter constructionis described in Walinsky.

U.S. Pat. No. 4,299,237 (Foti) is directed to an apparatus fortransferring thermal energy from a calorized fluid to an ear canal andtympanic membrane. In one embodiment, this apparatus comprises a rigidstructure made of a semi-rigid material and pre-shaped so as to conformto the internal geometry of an ear canal. Rigid internal struts keepopen a fluid circulation loop served by a fluid inlet tube and a fluidoutlet tube. In an alternative embodiment, the Foti apparatus comprisesan inflatable balloon element surrounding a hollow, central shaftcontaining a depth indicator for proper positioning of the device. Theballoon element is inflated and deflated through separate fluid inletand outlet tubes connected through a rigid ear mold adjoining theballoon element. The Foti apparatus in either embodiment is relativelyshort (typically about 32 mm in length) and relatively wide (overalldiameter of about 6 mm), therefore bearing little resemblance to avascular-type catheter which is typically several hundred millimeters inlength but with a diameter of only about three—four millimeters or less.Furthermore, the Foti device is designed to operate only at a relativelylow fluid pressure because it is not intended for dilating internal bodycanals and also because there is no need to force fluid through a verysmall diameter conduit over relatively long distances, again in contrastto a vascular-type dilatation catheter.

In the above-cited prior art, which is incorporated herein by reference,it should be understood that the term “multi-lumen” in the phrase“multi-lumen balloon catheters” typically means that the catheter shaftis multi-lumen (as opposed to the balloon segment in communication withthe catheter shaft). By contrast, my U.S. patent application Ser. No.07/929,305, of which this application is a continuation-in-part, isdirected to novel multi-lumen balloons. The multi-lumen balloons of myaforementioned invention are distinguished from the multi-lumen ballooncatheters of the prior art, as discussed above, in that the wallsdefining the lumens are formed as an integral part of the balloon. Theterms “integral part” and “integrally formed” as used in Ser. No.07/929,305 each mean that at least a lumen of the multi-lumen balloonshares a common wall portion with part of at least one inflatableballoon segment. By contrast, the prior art shows lumens that are formedas a part of a conventional catheter shaft and are defined by therelatively thick walls of that catheter (e.g. Segal et al.), catheterlumens that communicate with or terminate in a balloon segment (e.g.Banka and Segal et al.), and lumens in a shaft that passes coaxiallythrough a balloon segment (e.g. Banka, Sahota, and Walinsky).

In many conventional and non-conventional medical catheter applications,it would be desirable to provide a means for continuously transferringover an extended time period controlled amounts of thermal energy to oraway from one or more adjacent locations along or at the distal end ofan elongated, vascular-type catheter. Heat transfer can be effected, ofcourse, by circulating a heat transfer fluid inside a catheter lumen.This straightforward approach is complicated, however, by enormous andheretofore unsurmountable physical limitations and obstacles.

Thus, a single lumen catheter can certainly deliver a heat transferfluid to the closed distal end of the catheter. But, if the heattransfer fluid is at a temperature different from body temperature, theresult of this procedure would be to merely create a temporarytemperature gradient along the length of the catheter. At locationsdistal from the point where the fluid was introduced to the catheter,the temperature of the fluid in the catheter would tend to approach theinternal body temperature. Furthermore, even this temperature effectwould exist for only a relatively short time until the fluid at everypoint along the catheter gradually heated or cooled to body temperature.Clearly, this approach cannot be used to continually transfer controlledamounts of thermal energy to or away from internal body locations overan extended time period.

To effect continuous, controlled transfer of thermal energy to or from abody location adjacent the catheter therefore requires, at a minimum, atwo-lumen catheter construction. With such a two-lumen construction, acontinuous flow of heat transfer fluid can, at least in theory, beestablished. Fresh fluid at any desired temperature can be continuouslyintroduced at the proximal end of a first or inlet catheter lumen andpassed through that first lumen to a distal location inside the body,then passed through fluid connection means directly to the second oroutlet catheter lumen, and finally passed back along that second lumento be withdrawn at the proximal end as spent fluid for discarding orrecycling. If the continuous fluid flow rate through such a two-lumencatheter system is sufficiently rapid, this construction makes itpossible to establish and substantially maintain a fluid temperatureinside the catheter that is above or below normal body temperature atany location along the length of the catheter. Correspondingly, if thecatheter is constructed of a material which has good heat transferproperties and which is also sufficiently flexible so as to closelyconform to the surrounding body cavity, the temperature of the fluidinside the catheter can be transferred to adjacent portions of the bodythat are in contact with or in proximity to the catheter sidewalls.

There are problems, however, associated with a two-lumen catheterconfiguration for carrying heat transfer fluid. A principal problem withsuch a configuration, utilizing conventional catheter and balloonconstruction and materials, relates to the size of the final apparatus.It will be apparent to those skilled in the art that catheterconstructions intended for blood vessels and similar very small diameterbody passages must be of correspondingly small diameter. This sizeproblem is exacerbated by a two-lumen catheter construction, whether thelumens are configured side-by-side or concentrically. In either case, asignificant proportion of the limited space inside the blood vessel orother body passage is occupied by relatively thick catheter sidewallsleaving relatively little open cross-sectional area for circulatingfluids or as passageways for medical instruments and the like.

For example, the relatively thick sidewalls that define the lumens ofconventional multi-lumen catheters, such as in the prior art patentscited above, typically range from about 0.003 to about 0.010 inches orgreater. In part, the reason that conventional multi-lumen cathetershave utilized such thick sidewalls is because these devices arefabricated from materials that are not high in tensile strength. Mostballoon catheter shafts have conventionally been made by extrusion of athermoplastic material. The resulting shafts are typically notsubstantially oriented, therefore not high tensile strength. Becauserupture of one of these catheters while in use might cause air bubblesor dangerous fluids to leak into the blood stream resulting in death orserious injury, the catheter sidewalls had to be made thick enough toinsure safety and reliability. This was especially important where thecatheter was intended to carry fluid under pressure. Furthermore, suchthick-walled catheter lumens are not readily inflatable under fluidpressure nor readily collapsible under vacuum, thereby complicating theprocess of inserting or withdrawing these devices.

With a conventional balloon dilatation catheter used, for example, foran angioplasty procedure, a relatively narrow cross-sectional catheteropening due to the relatively thick catheter sidewalls might be anuisance but generally would not completely defeat the purpose of such acatheter. Such a device would still generally function as long assufficient fluid could gradually be transferred through the cathetershaft in order to inflate the balloon and thereby dilate the bloodvessel. By contrast, for a heat transfer catheter, the inability toestablish and maintain a relatively high fluid flow rate through thecatheter would completely defeat the purpose of continuouslytransferring controlled amounts of thermal energy to or away from remoteinternal body locations. A slow or uneven flow of heat transfer fluidthrough the catheter lumen would be unable to overcome the continuousheating or cooling effect of the surrounding body tissue along therelatively long length of the catheter. Moreover, if the heat transfercatheter was intended to be used in conjunction with a dilatationballoon, or with a guide wire, or with a medical instrument, a third, afourth or additional catheter lumens would need to be provided, eachdefined by its own relatively thick sidewalls, thereby furtherrestricting the already limited open, cross-sectional area.

Still another problem with the conventional thick-walled multi-lumencatheter is that the relatively thick sidewalls act as insulation andreduce heat transfer between any fluids inside and the surrounding bodytissue. Yet another problem with the conventional thick-walledmulti-lumen catheters is that the thick walls tend to be relativelyrigid and thus do not closely conform to the surrounding body canal,thereby further reducing heat transfer.

These and other problems with and limitations of the prior art cathetersin connection with heat transfer applications are overcome with the heattransfer catheters of this invention.

OBJECTS OF THE INVENTION

Accordingly, it is a general object of this invention to provide acatheter apparatus suitable for heat transfer applications inside aliving body together with methods for making and using such apparatus.

A principal object of this invention is to provide a heat transfercatheter with fluid lumens having at least in part very thin, highstrength sidewalls that are readily inflatable under fluid pressure andreadily collapsible under vacuum.

It is also an object of this invention to provide a heat transfercatheter having fluid lumens with very thin, high strength sidewallsthat have high heat transfer properties.

A further object of this invention is to provide a heat transfercatheter having fluid lumens with very thin, high strength sidewallsthat, when inflated under fluid pressure, closely conform to thegeometry of the surrounding body cavity.

A specific object of this invention is to provide a catheter apparatuscapable of continuously transferring controlled amounts of thermalenergy to or away from adjacent internal body locations that arerelatively distant from the point of entry of the catheter into the bodyover an extended period of time.

Still another specific object of this invention is to provide a heattransfer balloon dilatation catheter capable of dilating a remoteinternal body location while simultaneously delivering controlledamounts of thermal energy to or withdrawing controlled amounts ofthermal energy from an adjacent body location.

Yet another specific object of this invention is to provide a heattransfer catheter for enclosing a diagnostic or therapeutic instrumentwhile simultaneously transferring controlled amounts of thermal energyto or away from all or a portion of the instrument.

These and other objects and advantages of this invention will be betterunderstood from the following description, which is to be read togetherwith the accompanying drawings.

SUMMARY OF THE INVENTION

The heat transfer catheter apparatus of the present invention comprisesvery thin-walled, high strength thermoplastic tubular material defininga plurality of lumens, at least two of which are adjacent and readilyinflatable under fluid pressure and readily collapsible under vacuum.Fluid connection means are provided at or proximate to the distal endsof the two adjacent lumens to define a closed loop fluid containment andcirculation system whereby heat transfer fluid from a first, inlet lumenis passed directly to a second, outlet lumen such that a continuous flowof heat transfer fluid through the two lumens can be established andmaintained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic longitudinal sectional view of a heat transfercatheter apparatus according to one embodiment of the invention.

FIG. 2 is a cross-sectional view of the catheter apparatus of FIG. 1along the line 2-2.

FIG. 3 is a schematic longitudinal sectional view of a heat transferballoon dilatation catheter apparatus according to another embodiment ofthe invention.

FIG. 4 is an isometric view of a heat transfer balloon dilatationcatheter apparatus similar to FIG. 3 but also comprising three straight,perimetrical lumens adjacent to the balloon wall.

FIG. 5 is a cross-sectional view of the catheter apparatus of FIG. 4along the line 5-5.

FIG. 6 is an isometric view of a heat transfer balloon dilatationcatheter apparatus similar to FIG. 3 but also comprising a helical,perimetrical lumen having pin holes for delivering fluid to a bodycavity.

FIG. 7 is a cross-sectional view of the balloon portion of another typeof multi-lumen heat transfer balloon dilatation catheter apparatusaccording to another embodiment of this invention.

FIG. 8 is a cross-sectional view of the balloon portion of still anothertype of multi-lumen heat transfer balloon dilatation catheter apparatusaccording to the present invention.

FIG. 9 is a schematic, isometric, partial cross-sectional view of a heattransfer catheter according to still another embodiment of theinvention.

FIG. 10 is a schematic cross-sectional view of a heat transfer catheteraccording to yet another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In each of the drawings, as described below, it should be understoodthat the wall thicknesses of the catheter and balloon lumens have beengreatly exaggerated relative to other elements and to other dimensionsfor purposes of illustration.

FIG. 1 shows a schematic longitudinal sectional view of a heat transfercatheter apparatus 10 according to the present invention comprising asubstantially concentric, coaxial configuration of multiple lumens orchannels. The concentric, coaxial arrangement of the multiple lumens canbe better understood by reference to FIG. 2, a cross-sectional viewtaken along the line 2-2 of FIG. 1. Returning to FIG. 1, a first, innercatheter tube 12 defines a central conduit 11 receiving a guide wire 13.Catheter tube 12 may be of conventional, thick-walled construction or,alternatively, comprise very thin sidewalls. For purposes of thisinvention, the terms “very thin walls” or “very thin-walled” refer toelongated sleeves or catheters having sidewalls ranging in thicknessfrom about 0.0002 inches up to about 0.002 inches, and, in somepreferred embodiments, a wall thickness not exceeding 0.0009 inches. Bycomparison, the conventional “thick-walled” constructions of prior artmulti-lumen catheters typically range in thickness from about 0.003 toabout 0.010 inches or more. For purposes of this invention, the term“elongated” refers to catheter apparatus or to sleeves having an overalllength-to-diameter ratio of about 25:1 or greater. In the embodiment ofFIG. 1, if catheter tube 12 is of conventional construction, tube 12 mayprovide sufficient rigidity by itself for insertion of the apparatusinto a body canal or passageway. Alternatively, if inner catheter tube12 is of very thin-walled construction, wire guide 13, previouslypositioned using a guide catheter or other conventional manner, may beneeded in order to facilitate threading the catheter apparatus through ablood vessel or similarly narrow passageway. Inner catheter tube 12 maybe of single or multi-lumen construction depending on the number ofchannels desired for a particular application. Catheter tube 12 may beconfigured open at both ends, for example to fit over a wire guide 13,and to act as a channel to inject or drain fluid, or to contain adiagnostic or therapeutic device. Alternatively, tube 12 can also besealed at its distal end or configured in other advantageous ways.

Surrounding at least a portion of the length of inner catheter tube 12is a very thin-walled, inflatable and collapsible, elongated innersleeve 14 which may be, but need not be, at least partially sealed atits distal end to the outer surface of tube 12 so as to create a secondor intermediate lumen 16 comprising an annual region with a donut-likecross section surrounding catheter tube 12. The annular configuration oflumen 16 can be better understood by reference to FIG. 2. For example,if tube 12 has an external diameter of about 0.04 inches, sleeve 14 maycomprise biaxially-oriented polyethylene terephthalate (PET) and have aninner diameter of about 0.087 inches and a sidewall thickness of about0.0005 inches. Surrounding at least a portion of the length of sleeve 14is a very thin-walled, inflatable and collapsible, elongated outersleeve 20 which is sealed at its distal end to the outer surface of tube12 at a point distal from the distal end of sleeve 14 so as to create athird or outer lumen 22 comprising an annular region with a donut-likecross section surrounding sleeve 14. The annular configuration of lumen22 can be better understood by reference to FIG. 2. In the precedingexample, sleeve 20 may comprise biaxially-oriented PET and have an innerdiameter of about 0.125 inches and a sidewall thickness of about 0.00065inches. Fluid connection means 18, in this case comprising an openingbetween the open distal end of sleeve 14 and the inner wall of sleeve20, places the distal end of lumen 16 in direct fluid communication withthe distal end of lumen 22. Alternatively, the fluid connection meansmay comprise one or a plurality of apertures in the common wall means(i.e. in sleeve 14) separating lumens 16 and 22. In the foregoingexample, the total cross-sectional area available for inlet and outletfluid flow, as seen in FIG. 2, represents approximately 87% of theavailable cross-sectional area of the body canal in which the catheterapparatus is positioned. For the heat transfer catheters of thisinvention, at least about 60%, and preferably greater than about 80% ofthe available cross-sectional area of the body canal should be availablefor fluid flow. Although lumens 16 and 22 are shown in FIG. 1 as singlelumens, it should be appreciated that one or both of these lumens may befabricated as a multi-lumen structure, but obviously with some smallassociated loss of available fluid flow area because of additional wallmeans.

Catheter apparatus 10 as shown in FIG. 1 further comprises a first orproximal manifold section 30 and a second or distal manifold section 32.The distal end of manifold 30 is adapted to sealingly mate with theproximal end of manifold 32, for example by means of male and femalethreaded elements, 34 and 36 respectively, in combination with aresilient O-ring 38. Alternatively, manifolds 30 and 32 may beadhesively bonded to one another. Male element 34 of manifold 30 furthercomprises a centrally-located bore 40. Manifold 30 also comprises afluid inlet port 42 connected to a source of fluid via a fluid fitting,which may also comprise an inlet valve (not shown) or other fluid flowcontrol means, and an end seal 44. End seal 44 of manifold 30 alsocomprises a centrally-located bore 46. Bore 46 is sized so as to receivecatheter tube 12. Fluid sealing means (not shown) are provided betweenthe outside of tube 12 and the surface of bore 46 to prevent fluidleakage. Bore 40 is sized so as to receive both tube 12 and sleeve 14.The proximal end of sleeve 14 comprises fluid sealing means, such as anannular lip or flange 15 projecting radially outward and capable ofbeing bonded or sealed to an inner wall of manifold 30. Alternatively,the outside of the proximal end of sleeve 14 may be adhesively bonded tothe wall of bore 40.

Manifold 32 further comprises an outlet port 50, which may comprise anoutlet valve (not shown) or other fluid flow control means, a tapereddistal end 52 having a tubular projection 54, and a centrally-locatedopening 56 passing through tapered end 52 and projection 54. Opening 56is sized so as to receive catheter tube 12 and sleeves 14 and 20 whileleaving an open annular region defined by the outside of sleeve 14 andthe inside surface of sleeve 20 through which fluid can pass. Theoutside of the proximal end of sleeve 20 may be adhesively bonded to thewall of opening 56. Thus, after the distal portion of catheter apparatus10 is positioned in the body, fresh heat transfer fluid at a desiredtemperature, ordinarily (but not necessarily) different from normal bodytemperature, first enters manifold 30 through inlet port 42 (asillustrated by the fluid direction arrows), passes through the interiorcavity of manifold 30 into the proximal end of sleeve 14 at lip 15, thenpasses through inlet fluid lumen 16 to the distal end of sleeve 14, thenpasses directly through fluid connection means 18 into outlet fluidlumen 22, then passes back through lumen 22 to the proximal end ofsleeve 20, then passes into the interior of manifold 32 from which itexits through exit port 50. As used herein, the term “inlet fluid lumen”means a passageway or conduit of an elongated catheter through whichfluid flow is substantially in a direction from the proximal end towardthe distal end. Correspondingly, the term “outlet fluid lumen” means apassageway or conduit of a catheter through which fluid flow issubstantially in a direction from the distal end toward the proximalend. The spent heat transfer fluid exiting through port 50 may berecovered and heated or cooled (as necessary) to restore it to thedesired temperature and then recycled back to inlet port 42.

The heat transfer fluids that are useful in the practice of thisinvention include both gases and liquids, but are preferably liquid. Thefluid may be water or an aqueous solution, for example normal saline,provided the desired heating or cooling temperature is within the liquidrange of water, i.e. about 0-100° C. For special applications,particularly for operating temperatures below 0° C. or above 100° C.,other fluids, such as the various halogenated hydrocarbons (e.g.“Freon”), may be utilized. Obviously the selected fluid must be one thatwill be chemically compatible with the material from which the fluidlumens are constructed at the desired operating temperature.

As illustrated in FIG. 1, manifold sections 30 and 32 may comprisemetal, plastic or other suitable materials. Catheter tube 12, innersleeve 14 and outer sleeve 20 may comprise the same or differentthermoplastic materials. The choice of materials and fabricationtechniques may be adapted to meet particular design specifications or torealize particular properties of the completed apparatus. Some of thespecific fabrication techniques, material selections, and desirabledesign features that are within the scope of this invention arepresented below for purposes of illustration. Other advantageousvariations will be apparent to those skilled in the art, and suchobvious variations are also considered to be within the scope of thisinvention.

With regard to sleeves 14 and 20, it is preferred that these sleeves beof high tensile strength and able to withstand anticipated internalfluid operating pressures, which, for some applications, may be on theorder of about 200 psi and higher, while, at the same time, beingsufficiently thin-walled to have good heat transfer properties, toinsure good contact with the walls of the internal body cavity duringuse, and to minimize wasted internal space. These sleeves should also bereadily inflatable under fluid pressure and readily collapsible undervacuum to facilitate insertion and removal of the catheter apparatus. Torealize these combined objectives, sleeves 14 and 20 should havesidewalls not exceeding a thickness of about 0.002 inches, preferablyless than about 0.001 inches, and, for some embodiments, less than0.0009 inches. Sleeves 14 and 20 can be fabricated from an orientablepolymeric material, for example using tubing extrusion and blow moldingtechniques, such as those taught in my copending U.S. patentapplications Ser. No. 08/059,725 and Ser. No. 07/929,305.Biaxially-oriented PET sleeves can be prepared as thin as 0.0002 inches,for example, while retaining adequate tensile strength to insure againstany ruptures while in use. Because thicker walls of biaxially-orientedPET tend to be somewhat rigid, it is preferred that such sleeves forthis invention have sidewall thicknesses ranging from about0.0002-0.0009 inches. In an alternative embodiment for certainapplications, sleeves 14 and/or 20 may be fabricated from weaker butmore flexible materials. For example, polyurethane sleeves may havesidewalls as thick as about 0.005 inches while still retaining thenecessary flexibility for expansion, collapse, and conformity with thewalls of the internal body cavity while in use. It will be understoodthat, for any given sleeve material, thinner sleeves will have betterheat transfer properties than thicker sleeves.

For most applications, including all dilatation applications, it ispreferred that fluid-carrying sleeves 14 and 20 be relatively inelastic.Fabrication of sleeves 14 and 20 from biaxially-oriented PET, asdiscussed above for example, would yield very thin-walled, highstrength, relatively inelastic sleeves. Any polymeric material capableof being oriented in at least one direction with resultant enhancementof mechanical properties, particularly strength, could be used tofabricate one or more of the sleeves and catheters of this invention.Depending on the specific apparatus construction and intendedapplication, such materials include PET, nylon, crosslinked polyethyleneand ethylene copolymers, urethanes, vinyls, and Teflon, among others. Insome applications, it may be preferred to fabricate outer sleeve 20, orboth sleeves 14 and 20 from an elastomeric material. One suchapplication would be where only relatively low fluid pressures areneeded, for example where the catheter apparatus does not include adilatation balloon and is not expected to be used in a dilatationprocedure. Another such application would be where variations ininternal anatomy would prevent an inelastic outer sleeve from makinggood heat transfer contact with the walls of the internal cavity orpassageway.

If sleeves 14 and 20 are fabricated from PET, in addition to containinga heat transfer fluid in accordance with this invention these sleeveswould also be capable of transmitting microwave energy, Nd:YAG laserenergy, UV laser energy, and others from the proximal to the distal endof the apparatus. Also, if the fluid-carrying sleeves are fabricatedfrom a suitable material, such as biaxially-oriented PET or PTFE(Teflon), the catheter apparatus would be capable of circulatingcryogenic fluids for selective freezing of tissue such as canceroustumors. In this case, for certain applications, it may be necessary toutilize multiple lumens so as to combine heating of the catheter viathis technology along most of the length of the catheter while havingthe cryogenic freezing occur only at a specific desired location at ornear the distal end of the catheter apparatus. The heating would preventthe entire catheter from freezing, thereby damaging tissue areas thatshould not be treated. For example, multiple lumens inside catheter tube12 could be used to circulate a cryogenic fluid while sleeves 14 and 20contained a heating fluid to insulate adjacent tissue along the lengthof the catheter except for the distal end beyond the end of sleeve 20.In still another embodiment, the distal end of tube 12 may communicatewith a balloon element, which could then also provide heating or coolingeffects. Simultaneous selective heating and cooling can also similarlybe provided with the catheter apparatus according to this invention; or,differential heating or cooling can be provided where, for example, oneside of the catheter is hotter or cooler than the other side in order toprovide for treatment of asymmetric anatomical features. Alternativeembodiments of the catheter apparatus, as hereinafter described, mayalso be adapted for such differential heating and/or coolingapplications.

In still another embodiment of this invention, the diameters and wallthicknesses of tube 12 and of sleeves 14 and 20 may be selected suchthat lumens 16 and 22 have substantially equal cross-sectional areas forfluid flow. Alternatively, by adjusting the diameters of one or more oftube 12, sleeve 14 and sleeve 20, the cross-sectional areas of annularlumens 16 and 22 may be varied to create different pressure gradientsand fluid flow rates. In another fabrication variation, sleeves 14 and20 may be formed so as to have substantially constant cross-sectionaldiameters along their respective lengths at constant fluid pressure.Alternatively, one or both of sleeves 14 and 20 may be formed so as tohave varying cross-sectional diameters along their lengths in order togenerate particular flow patterns, for example to cause turbulent fluidflow at a desired location for purposes of increased heat transfer.

FIG. 3 is a schematic, cross-sectional view of an alternative embodimentof a heat transfer catheter in accordance with this invention. In FIG.3, catheter apparatus 60 comprises a multi-lumen balloon dilatationcatheter comprising a first or inner sleeve 62, defining an open spaceor inner lumen 64, and a second or outer sleeve 66 surrounding innersleeve 62 so as to create an outer annular lumen 68. Inner sleeve 62 isformed open at its distal end and spaced from the inner wall of sleeve66 so as to create a fluid connection 70. Outer sleeve 66 is formedclosed at its distal end. The closed distal end of sleeve 66 is at apoint that is distal from the open distal end of sleeve 62 so that fluidmay pass through fluid connection means 70 from fluid inlet lumen 64into fluid outlet lumen 68.

Proximate to its distal end, outer sleeve 66 comprises a dilatationballoon segment 72. Balloon segment 72 is preferably of very thin-wall,high strength construction, substantially inelastic, and readilyinflatable under fluid pressure and readily collapsible under vacuum. Ina preferred embodiment of this variant, at least sleeve 66 and balloonsegment 72 comprise a unitary, integral and seamless unit wherein saidsleeve portion and said balloon segment are integrally formed inaccordance with the teachings of my copending U.S. patent applicationSer. No. 08/059,725. In this embodiment of the invention, fresh heattransfer fluid is introduced into the proximal end of inner lumen 64,passes through lumen 64 and fluid passage means 70 directly into outerlumen 68, through the interior of balloon segment 72, and then backalong lumen 68 to the proximal end of the apparatus where the spentfluid is withdrawn. During use, fluid flow control means, such asvalves, at the proximal ends of lumens 64 and 68 may be used to maintainfluid pressure inside lumens 64 and 68 at a level that is sufficient tofully inflate balloon segment 72. Alternatively, a restriction can beincorporated into the manifold so as to create pressure in the lumens.

The heat transfer balloon dilatation catheter apparatus of FIG. 3 may beutilized in several different ways. In one embodiment, lumens 64 and 68may be partially inflated with fluid in order to provide the stiffnessneeded to insert the catheter. Once the apparatus is properlypositioned, the fluid pressure may be increased so as to fully inflatethe dilatation balloon segment 72. Alternatively, a separate rod orhollow tube 74, as illustrated in FIG. 3, can be inserted through innerlumen 64 to provide stiffness. Tube 74 may be a solid rod or a hollowtube defining another lumen 76. Tube 74 may also comprise an elongateddiagnostic or therapeutic device that is either permanently attached tothe catheter apparatus or is removable, so that the catheter apparatuscan be disposable and the medical instrument reusable or vice versa.Examples of instruments that could be utilized in such a combinationcatheter apparatus include microwave antennas, lasers, ultrasoundprobes, induction coils, and electric heating elements.

The requisite properties of sleeves 62 and 66 in FIG. 3, the materialsfrom which these sleeves are prepared, and the sleeve fabricationtechniques are similar to those discussed above for sleeves 14 and 20respectively in FIG. 1. Thus, sleeves 62 and 66, including balloonsegment 72, must have sufficient strength to withstand anticipatedinternal fluid operating pressures while, at the same time, beingsufficiently thin-walled to have good heat transfer properties, toinsure good contact with the walls of the internal body cavity duringuse, and to minimize wasted internal space. These sleeves should also bereadily inflatable under fluid pressure and readily collapsible undervacuum. To realize these combined objectives, sleeves 62 and 66,including balloon segment 72, generally have sidewalls not exceeding athickness of about 0.002 inches. Similar to sleeves 14 and 20 in FIG. 1,sleeves 62 and 66 in FIG. 3 may be fabricated from an orientablepolymeric material, for example using tubing extrusion and blow moldingtechniques. For this embodiment of the invention, sleeves 62 and 66 and,particularly, balloon segment 72, should be relatively inelastic suchthat, when fully inflated and undeformed, balloon segment 72 dilates toa predetermined, repeatable size and shape. Biaxially-oriented PETsleeves having sidewall thicknesses of about 0.0002-0.0009 inches are aparticularly advantageous embodiment of this version of the invention.

The heat transfer balloon dilatation catheter apparatus as describedabove may further comprise one or a plurality of adjacent lumens locatedexternally of the maximum realizable dimension of the inelastic balloonsegment 72 and adjacent to the wall of the balloon when the balloon isfully inflated and undeformed. In this embodiment, the balloon segmentshares with each said adjacent, external lumen a single-layer,integrally formed wall section comprising a portion of the balloon walland separating the interior of the balloon from the interior of theadjacent, external lumen. The balloon comprises a very thin, flexible,high strength, substantially inelastic material having a wall thicknessof less than about 0.0015 inches, preferably less than about 0.0009inches. The preparation and use of such multi-lumen balloon dilatationcatheters is taught in my copending U.S. patent application Ser. No.07/929,305.

FIGS. 4-6 illustrate one set of embodiments of a heat transfer,multi-lumen balloon dilatation catheter apparatus according to thepresent invention. FIG. 4 shows a previously-formed heat transferballoon dilatation catheter apparatus 230, generally comparable toapparatus 60 of FIG. 3, comprising an outer sleeve 232 (best seen inFIG. 5) having a closed distal end 233 and a concentric, coaxial innersleeve 234. This structure is clearly evident in FIG. 5, across-sectional view along the line 5-5 of FIG. 4. Outer sleeve 232comprises a balloon segment 236 having conical or tapered ends 238 and240. Thus, in one embodiment in accordance with this invention, thecatheter apparatus of FIG. 4 can be operated as a heat transfer cathetercomparable to FIG. 3, wherein heat transfer fluid enters through thelumen defined by inner sleeve 234, dilates balloon segment 236, andexits through the annular lumen defined between sleeves 232 and 234.Other embodiments utilizing the apparatus of FIG. 4, as discussed below,are also contemplated, however. In accordance with the techniquedescribed in U.S. Ser. No. 07/929,305, mandrels or forming wires may bepositioned along the external surface of outer sleeve 232 and a tube 250(best seen in FIG. 5) of a heat-shrinkable thermoplastic thereaftershrunk around sleeve 232 so as to create one or more of adjacent,external lumens 242, 244, and 246, each integrally formed with a portionof sleeve 232.

Fluid flow connection means, for example one or more apertures, may beprovided in the integrally formed wall means that separates the interiorof balloon segment 236 and one or more of the adjacent, external lumens242, 244 and 246. In this embodiment, instead of having coaxial innersleeve 234, fluid may be supplied to balloon segment 236 through sleeve232 and withdrawn through an externally-extending adjacent, externallumen such as lumen 242. As seen in FIG. 4, external, adjacent lumen 242can be formed so as to run the entire length of sleeve 232, includingballoon segment 236 and conical ends 238 and 240. Thus, in still anotherembodiment of this invention, an apparatus similar to that shown in FIG.4 but having two perimetrical lumens like lumen 242 running the entirelength of sleeve 232 could be used to deliver heat transfer fluid to abody location distal of balloon segment 236. The flow of heat transferfluid, in through one of said perimetrical lumens and out through theother, would not be significantly interrupted even during dilatation ofballoon segment 236. Similarly, and for other applications, external,adjacent lumen 244 can be formed so as to run from one end of the middleor working section of balloon 236 to the other. Similarly, external,adjacent lumen 246 can be formed so as to begin and end within theworking section of balloon 236. By proper selection of the formingwires, external, adjacent lumens can be created of the same or differentdiameters, of uniform or non-uniform cross-section, and of circular orother cross-sectional shape, as desired for particular applications.Employing a similar preparation technique, a heat transfer balloondilatation catheter apparatus can be prepared as shown in FIG. 6 whereinan external, adjacent lumen 252 runs in a helical pattern around theoutside wall of balloon 236. Helical lumen 252 may comprise, in oneembodiment, a plurality of pinholes 254 along its length to preciselydeliver medication or other fluids to select body locations.

FIGS. 7 and 8 illustrate alternative embodiments of a heat transfer,multi-lumen balloon dilatation catheter apparatus according to thepresent invention. The preparation and use of multi-lumen balloonshaving cross-sectional configurations similar to those shown in FIGS. 7and 8 is also taught in my copending U.S. patent application Ser. No.07/929,305. Thus, the nine-lumen balloon structure of FIG. 7 is preparedeither by heat-shrinking a thermoplastic sleeve over the four-lobeinterior structure (which, in turn, is made by blow molding a five-lumenextruded preform) or by blow molding a five-lumen extruded preforminside a thermoplastic sleeve.

In FIG. 7, one or more of lumens 126, 127, 128 and 130, for example,could be utilized as inlet lumens for heat transfer fluid, and one ormore of lumens 134, 135, 136 and 138 could be utilized as outlet lumensfor heat transfer fluid, by providing fluid connection means betweenadjacent inlet and outlet lumens. For example, lumen 126 could beprovided with apertures in its sidewall to permit fluid flow into one orboth of adjacent lumens 134 and 138. Correspondingly, lumen 130 could beprovided with apertures in its sidewall to permit fluid flow into one orboth of adjacent lumens 135 and 136. In this example, inlet lumen 126and outlet lumens 134 and 138 could carry heat transfer fluid at a firsttemperature, while inlet lumen 130 and outlet lumens 135 and 136 couldcarry heat transfer fluid at a second, different temperature. Thoselumens not being utilized to circulate heat transfer fluid, such ascentral lumen 124 and side lumens 127 and 128 in the above example,could be utilized to enclose a medical instrument, a guide wire, or thelike, or to provide fluid passageways for medicine delivery, fluiddrainage, or perfusion applications. Although FIG. 7 illustrates amulti-lumen dilatation balloon having nine lumens, at least two of whichmust be interconnected to provide fluid flow in accordance with thepresent invention, it will be understood that similar preparationtechniques could be used to prepare similar multi-lumen balloonstructures having more or fewer lumens than nine.

The structure of FIG. 8 is prepared by blow molding a nine-lumenextruded preform of appropriate starting geometry, also as described inSer. No. 07/929,305. Similar to FIG. 7, FIG. 8 illustrates a nine-lumenballoon structure in which one or more of lumens 426, 427, 428 and 430,for example, could be utilized as inlet lumens for heat transfer fluid,and one or more of lumens 134, 135, 136 and 138 could be utilized asoutlet lumens for heat transfer fluid, by providing fluid connectionmeans between adjacent inlet and outlet lumens. For example, lumen 427could be provided with apertures in its sidewall to permit fluid flowinto one or both of adjacent lumens 434 and 435. Correspondingly, lumen428 could be provided with apertures in its sidewall to permit fluidflow into one or both of adjacent lumens 436 and 438. In this example,inlet lumen 427 and outlet lumens 434 and 435 could carry heat transferfluid at a first temperature, while inlet lumen 428 and outlet lumens436 and 438 could carry heat transfer fluid at a second, differenttemperature. As discussed above with respect to FIG. 7, those lumens notbeing utilized to circulate heat transfer fluid could be utilized forother applications. It will be understood that similar preparationtechniques could be used to prepare similar multi-lumen balloonstructures having more or fewer lumens than nine.

FIG. 9 illustrates yet another embodiment of this invention. In FIG. 9,catheter apparatus 80 comprises two concentric, coaxial lumensconsisting of an inner inlet lumen and an outer outlet lumen. The innerinlet lumen 82 defined by inner sleeve 84 is surrounded by a closed-endouter sleeve 86 of larger diameter than inner sleeve 84 thereby definingan annular outlet lumen 88 having a donut-like cross section. Innersleeve 84 includes fluid communication means, such as multiple aperturesor side holes 90 which permit fluid to pass directly from inlet lumen 82to outlet lumen 88 at or near the distal end of inlet lumen 82. Theproximal end of inlet lumen 82 is coupled to fluid inlet means 83, forexample a one-way valve. Correspondingly, the proximal end of outletlumen 88 is coupled to fluid outlet means 89, for example a one-wayvalve. Housing means 85 may be provided to facilitate coupling the inletand outlet lumens to their respective inlet and outlet valves.

Similar to the embodiment shown in FIG. 3, the catheter apparatus ofFIG. 9 may be filled with fluid and pressurized in order to stiffen itsufficiently to facilitate insertion or, alternatively, a solid rod orhollow tube (not shown) can be inserted into one of the lumens toprovide the necessary stiffness. Instead of a rod or tube, an elongateddiagnostic or therapeutic device may be used to provide stiffness. Suchdevice may either be permanently attached to the catheter apparatus orit may be removable, so that the catheter apparatus can be disposableand the medical device reusable or vice versa.

FIGS. 1-6 and 9 as discussed above illustrate embodiments of thisinvention in which the heat transfer fluid inlet and outlet lumens areconcentric and coaxial. This configuration is relatively easy tomanufacture and generally permits maximum fluid flow for any givenexternal catheter diameter because a single-layer wall means (forexample, sleeve 14 in FIGS. 1 and 2, sleeve 62 in FIG. 3, sleeve 234 inFIG. 5, and sleeve 84 in FIG. 9) can serve as both the outer wall of aninner inlet lumen and as the inner wall of an outer, annular-shapedoutlet lumen. Other configurations of inlet and outlet lumens, however,are also within the scope of this invention.

FIGS. 7 and 8 illustrate two embodiments wherein the inlet and outletlumens are not in a concentric, coaxial configuration. Another suchalternative configuration is illustrated in FIG. 10.

FIG. 10 is a schematic cross-sectional view of a different lumenconfiguration for another heat transfer catheter 100 in accordance withthis invention. In FIG. 10, outer sleeve 102 surrounds and encloses twoinner sleeves 104 and 106 of smaller diameter which define respectivelylumens 108 and 110. Also shown in FIG. 10, enclosed within outer sleeve102 but external of lumens 108 and 110, is a central longitudinal member112 which may, in alternative embodiments, comprise a rod, a hollowtube, or a diagnostic or therapeutic instrument, or a combination of oneor more. If, as illustrated in FIG. 10, sleeves 104 and 106 and member112 are of such size and geometry as to not fill all of the interiorspace enclosed by outer sleeve 102, upon fluid inflation an irregularlyshaped lumen 114 would also be created inside sleeve 102. Thus, in thisembodiment, lumens 108 and 110 could be utilized as fluid inlet lumensfor introducing heat transfer fluid to catheter apparatus 100, and lumen114 utilized as the fluid outlet lumen. Fluid connection means (notshown), such as holes or apertures in sleeves 104 and 106, are providedto establish a flow of the heat exchange fluid from inlet lumens 108 and110 to outlet lumen 114.

The catheter configuration illustrated in FIG. 10 facilitates a numberof advantageous variations on the basic invention. For example, thecatheter apparatus 100 of FIG. 10 can, similar to the embodiments ofFIGS. 7 and 8, provide heat transfer fluid at two differenttemperatures, for example one for selective heating, the other forselective cooling. Different fluid flow rates can also be established ininlet lumens 108 and 110. Inner sleeves 104 and 106 may be either of thesame or different diameters, wall thicknesses, and materials. By makingone of the inner sleeves of a larger diameter than the other, upon fluidinflation member 112 will be displaced off-center and moved closer toone side of the inner wall of sleeve 102 than the other side. Thisembodiment may be useful where member 112 is a medical instrument. Asimilar result could be achieved by selectively inflating only one ofthe two inner sleeves 104 and 106.

It will be understood that a catheter apparatus according to thisinvention as illustrated in FIG. 10 could be prepared with only oneinner sleeve (i.e. only one fluid inlet lumen) or, alternatively, withthree, four or more inner sleeves instead of the two shown. It will alsobe understood that for any of the catheter apparatuses within the scopeof this invention the heat transfer inlet and outlet lumens can beconfigured to run substantially the entire working length of thecatheter or to occupy only a discrete, predetermined portion of thecatheter. For example, the heat transfer inlet and outlet lumens maycommence at the point where the catheter enters the body and terminateat a location intermediate of the distal end of the catheter.Alternatively, the heat transfer inlet and outlet lumens may be definedby conventional “thick-walled” sidewalls along a proximal section of thecatheter, and defined by very thin sidewalls of about 0.0002-0.002inches thickness only along a distal section of the catheter. In thisconstruction, heat transfer would be minimized along the proximal,thick-walled section of the catheter and maximized at the thin-walleddistal end.

Since certain changes may be made in the above-described apparatuses andprocesses without departing from the scope of the invention hereininvolved, it is intended that all matter contained in the abovedescription shall be interpreted in an illustrative and not in alimiting sense.

1. Fluid circulation catheter apparatus comprising in combination: anelongated inlet fluid lumen having proximal and distal ends, said inletlumen being defined by inlet lumen wall means and having fluid inletmeans proximate to said proximal end; an elongated outlet fluid lumenhaving proximal and distal ends, said outlet lumen being defined byoutlet lumen wall means and having fluid outlet means proximate to saidproximal end; and fluid connection means whereby substantially all fluidwould pass directly from said inlet lumen to said outlet lumen. 2.Catheter apparatus according to claim 1 further comprising a fluidinside said inlet and outlet lumens, said fluid being maintained at asubstantially constant temperature which is different from normal bodytemperature.
 3. Catheter apparatus according to claim 1 further whereinsaid fluid connection means is located proximate to said distal ends ofsaid inlet and outlet lumens.
 4. Catheter apparatus according to claim 1further comprising single-layer, integrally formed wall means comprisingat least a portion of said inlet lumen wall means and at least a portionof said outlet lumen wall means, said integrally formed wall meansseparating the interior of said inlet lumen from the interior of saidoutlet lumen.
 5. Catheter apparatus according to claim 4 wherein saidfluid connection means comprises at least an aperture in said integrallyformed wall means. 6-73. (canceled)
 74. A catheter system to transferthermal energy to or away from an internal body location and/or a bodyfluid by heat transfer to or from a working fluid, the systemcomprising: an inlet lumen; and, an outlet lumen, the outlet lumencoupled to the inlet lumen so as to transfer the working fluid betweenthe two, the outlet lumen having a structure to induce turbulence in thebody fluid or in the working fluid, and wherein the outlet lumen furthercomprises at least one shape or surface feature that induces turbulencein a working fluid passing through that lumen.
 75. A method of changingthe temperature of an internal body location and/or a body fluid, themethod comprising the steps of: providing an inflatable heat transferelement, the inflatable heat transfer element formed by at least aninlet lumen and an outlet lumen, at least one of the inlet lumen or theoutlet lumen having a turbulence-inducing shape; inserting theinflatable heat transfer element into a vascular system; delivering acirculating working fluid from a working fluid supply to the inflatableheat transfer element, the temperature of the circulating working fluidbeing different from that of the body fluid in the vascular system;inflating the inflatable heat transfer element with the circulatingworking fluid; inducing turbulence in the working fluid or in the bodyfluid by circulating the working fluid through the lumen having theturbulence-inducing shape, thereby enhancing heat transfer between thecirculating working fluid and the body fluid; and, returning the workingfluid to the working fluid supply via the outlet lumen.
 76. A method fortreating a patient by providing heating or cooling at an internal bodylocation and/or to a body fluid, the method comprising the steps of:providing a catheter system comprising a catheter and a heating orcooling element attached to a distal end thereof, the heating or coolingelement employing fluid mixing-inducing surface features; inserting thecatheter through the vascular system of the patient to place the heatingor cooling element at a desired location along the vascular system;circulating heat transfer fluid at a temperature different from that ofthe vascular system through the heating or cooling element; and,transferring heat between the heating or cooling element and the bodyfluid in the vascular system, whereby the body fluid is heated orcooled; wherein the mixing-inducing surface features are configured tocause mixing in the heat transfer fluid circulating through the heatingor cooling element and/or in the body fluid in the vascular systemhaving the heating or cooling element.
 77. A method for cooling apatient's body intravascularly, the method comprising the steps of:providing a catheter system comprising a catheter and a heating orcooling element attached to a distal end thereof, the heating or coolingelement having a mixing-inducing shape and/or surface feature; insertingthe catheter through the vascular system of the patient to place theheating or cooling element at a desired location inside the patient;circulating heat transfer fluid at a temperature different from that ofthe vascular system through the heating or cooling element including atleast the element portion having the mixing-inducing shape and/orsurface feature to create turbulence in the heat transfer fluid; and,transferring heat between the patient's vascular system and the heatingor cooling element.